500 – 700 million years ago, even before dinosaurs roamed the Earth, jellyfish were drifting along on ocean currents. Jellies are among the most spectacular and mysterious marine species in the world. They are the oldest multi-organ animal and have morphed into more than 2,000 different jellyfish species. Some live in freshwater, but jellies can be found in every ocean. Some sea jellies survive close to the surface while others dwell in extreme depths, glowing with bioluminescence in the pitch black water near the bottom of the ocean. Many scientists and deep ocean explorers expect to discover countless more beautiful jiggly jellyfish as they explore deep sea canyons, and other extreme water conditions near underwater volcano vents and in the harsh frozen temperatures of arctic waters. [72 Photos]

Jellyfish go with flow and have drifted along on ocean currents for millions of years, even before dinosaurs lived on the Earth. Few marine creatures are as mysterious and intimidating as jellyfish. Though easily recognized, these animals are often misunderstood. Sea nettles often have riders on their bodies, sometimes offering a place for small living organisms to be able to move around and sometimes being the food source for the organism. There is a reddish tint on the bell of the Pacific Sea Nettle or West Coast Sea Nettle which can span over 3 feet. This is a distinctive characteristic along with maroon tentacles that identify this particular species of jellyfish. The tentacles can be up to 15 feet long. Photo #1 by luna

For 25 years, the Discovery Channel has been showing Shark Week, a week’s worth of shark-orientated programming meant to educate but with plenty of fear factor. For some people, divers, scientists and people who hang out at the beach, sharks are a reality every day of the year. Like big, bad, beautiful wolves, people have long feared the predators prowling the deep and some shark species were hunted until their numbers were threatened. Sharks both fascinate us and fill us with fear, so here’s an up-close look at great whites, hammerheads, tiger sharks, bull sharks, whale sharks, lemon sharks, gray nurse sharks, and other sharks . . . all sprinkled with shark facts. We think sharks are jawesome and swimming with sharks is a pure adrenaline rush! [60 Photos, 10 Videos]

When you see sharks, like this Jaws type, wouldn’t you get out of the water? For a quarter of a century, the Discovery Channel has been showing a week’s worth of shark-orientated programming. We’ve gathered 60 shark photos and 10 videos to celebrate Shark Week, but for some divers and researchers who deal with the underwater world every day, every week is Shark Week. Photo #1 by free wallpaper